Do not reuse listener across tests

A single PlayerTestListener reused across tests may make
flaky tests more difficult to debug - if multiple tests are
run in one invocation.

PiperOrigin-RevId: 756688056

Author: ychaparov

libraries/transformer/src/androidTest/java/androidx/media3/transformer/CompositionPlayerSeekTest.java

@@ -95,12 +95,13 @@ public class CompositionPlayerSeekTest {
 
   private final Context applicationContext =
       getInstrumentation().getContext().getApplicationContext();
-  private final PlayerTestListener playerTestListener = new PlayerTestListener(TEST_TIMEOUT_MS);
 
+  private PlayerTestListener playerTestListener;
   private SurfaceView surfaceView;
 
   @Before
   public void setUp() {
+    playerTestListener = new PlayerTestListener(TEST_TIMEOUT_MS);
     rule.getScenario().onActivity(activity -> surfaceView = activity.getSurfaceView());
   }